The last time I had my boat out I was on my way back probably about 40 miles and one of the motors would drop 300-600 rpm for maybe 5-10 seconds than jump back up. It only did it about four times and it never stalled but obviously something isn't right, does anyone have any ideas on what would cause that? Their stock 330hp, NA 454's, I also put after market electronic ignition kits on them. Any thoughts are appreciated/ Thanks, Eric.

Sounds like you may be getting a misfire on one cylinder. If they have not been replaced in a while, it may be time for cap, rotor, plugs, and plug wires.

Dave